Brian, good idea and I appreciate and share your methods on this subject.
First and ironically, I seriously dislike and object to being photographed in public w/o my permission, especially by amateurs and tourists. If I see a camera crew or a PJ working, I generally avoid the situation.
Conversly, as a college student and for a short time after graduation I worked the streets of No Virginia and DC at every opportunity and had numerous photos published in small and big time newspapers.
At this point, general street photography doesn't interest me much at all. To me, with the advent of automation and then the digital revolution, it seems practically everyone is a shutterbug. Not only that but a large portion of those seem to be middle-aged men grabbing pics of pretty girls. As I pass 40 and start to see some grey in my whiskers I've decided I don't want to be one of "them". And, as much as I like pretty girls, the results typically hold my interest for a few seconds at best.
The exception to this opinion for me is the occasion of special events or exotic places in which case I'll work the streets searching for something I feel is truly interesting. Such as:
In my experience, in larger cities and especially tourist centers people don't mind being photographed or just as often are too busy to notice or care. In smaller cities, towns and rural areas people do tend to notice and care. Also in larger cities my experience is people are less apt to be friendly and cooperative. Whereas in other places people expect to be asked and are then more willing to cooperate. The exception to this for me being that when I carried press credentials and a big camera bag people did notice, wanted their photo taken, often wanted to be paid and would request a copy of the photo and/or publication.
In my area of the US people are generally friendly and polite and expect the same in return. Taking someones photo without permission is often considered rude and being rude 'round chere is a good way to get your ass kicked. Having lived here for most of my adult life I've pretty much adopted the same attitude. I don't ever sneak pics of people on the street, I always make sure they notice me and approve and I usually speak with them if possible at least afterwards. If I was a busy Pro on the streets this method might prove impractical, but for the little street shooting I do when I'm home it works well for me.
At work part of my job is to document the daily happenings on our ships and to back up the full-time Pro's when things get busy (I'm a Communications/Radio Officer for a small private fleet). When I join a ship and introduce myself at a meeting or meal I always ask if anyone minds or objects to being photographed. Our ship's crews are deliberately very culturally diverse and quite a few people do object for various reasons. Unfortunately for them they don't really have a choice as a paid crew member, but do take note and try to be considerate of their wishes without compromising the performance of my duties. Also we operate webcams on our ships and upload almost constantly via satellite. I always remind the crew of this and make sure everyone is aware of the webcam locations.
While legalities and ethics must be considered for obvious reasons, I feel etiquette is just as important if not more so. Etiquette is a major part of human relations and I feel life is ultimately an exercise in how we relate to our fellow humans, our environment and fellow creatures. IMO, at the end of our day how we did and what we learned is all we are left with.
Whew !
cheers